I'm no shill (see my other comments here), but I really don't think this is anything. Look at the statement in the context of the entire sentence and the larger email thread. The email prior to this comment is describing some situation that they hope will work out as they want. Then we see this in response:

With fingers crossed, the old rabbit's foot out of the box in the attic, I will be sacrificing a chicken in the backyard to Moloch . . .

It seems pretty obvious to me that what we're seeing here is a joke about three different methods of trying to get good luck or a desired outcome.

Method 1 = Crossing fingers

Method 2 = Using a rabbit's foot

Method 3 = Making a sacrifice to a god

Honestly, I don't see anything remotely sinister here unless you insist that she really meant to do these things literally (i.e. cross her fingers, go into the attic to get a rabbit's foot, then, still having her fingers crossed, sacrifice a chicken), and even then there's no reason in this particular instance to think "chicken" is code for anything, since an actual chicken would make perfect sense here.

It's things like this that teach us the lesson that we need to be ever-vigilant against confirmation bias.